UNITED NATIONS (Reuters) - The United Nations human rights chief on Saturday urged several countries to intensify their investigations of alleged sexual abuse of young children in the Central African Republic by French and African soldiers posted in the conflict-torn nation.

A 6-page internal U.N. report obtained by Reuters detailed the alleged abuse by troops from France, Chad and Equatorial Guinea between December 2013 and June 2014 at a center for displaced people at M’Poko airport in the Central African Republic capital, Bangui.

France has launched an investigation into the allegations and has identified some of the French soldiers suspected of involvement. It is not clear what Chad and Equatorial Guinea have done.

"In the wake of the revelations of alleged serious sexual abuse of children, currently under investigation by the French authorities, my office has taken a deeper look into these issues and the extent of the follow-up into alleged serious violations," said U.N. human rights chief Zeid Ra'ad Al Hussein.

"Some of these incidents have been at least partly investigated, and some states have apparently sanctioned some of the soldiers involved," he said in a statement issued in Geneva.

The 6-page U.N. report said child victims interviewed by U.N. staff alleged they had performed oral sex on the French troops, while accusing soldiers from Equatorial Guinea and Chad of sodomizing children.

"It is important to do a thorough review of what happened in the past, but also to drive home the message that there must be no repetition of these dreadful acts now or in the future, he said.

"We need to get to the bottom of what precisely was done by whom and when," he added. "There must be accountability for serious crimes, no matter who commits them."

Even though none of the implicated troops were U.N. peacekeepers at the time of the alleged abuse, the United Nations has come under fire due to its slow response after preparing its initial 2014 report on the allegations. The U.N. only began talking openly about the issue a month ago, after an article on the allegations appeared in The Guardian newspaper.

The United Nations is currently conducting an internal investigation of its handling of the allegations.

France intervened in Central African Republic, a former colony, some 19 months ago to stem violence between Christian militias and largely Muslim Seleka rebels who had seized power. It started withdrawing some of its 2,000 troops this year, handing over to U.N. peacekeepers.